Search

Amplifiers based on Josephson junctions allow for a fast and noninvasive readout of superconducting qubits. Motivated by the ongoing progress toward the realization of fault-tolerant qubits based on Majorana bound states, we investigate the topological counterpart of the Josephson bifurcation amplifier. We predict that the bifurcation dynamics of a topological Josephson junction driven in the appropriate parameter regime may be used as an additional tool to detect the emergence of Majorana bound states. [ABSTRACT FROM AUTHOR]

Given that most large-scale complex engineering systems need to be simplified and layered before being designed, a hierarchical approach is necessary to ensure a global and structured understanding of the whole system, including involved stakeholders, use cases, and associated requirements. Even though use cases in themselves are quite intuitive, the process around them is a much bigger challenge since it usually varies from one situation to another. The key step in the proposed methodology is the identification of the system dimensions as a mean to organize use cases. In this article, we propose a framework to address the system dimensions by defining useful functional spaces and accordingly classify the scenarios. As a case study, we analyze and model a cooperative intersection safety system using a hierarchical method to represent use cases. The key challenge in enhancing intersection safety is to identify vehicles that have a high potential to be involved in a collision as early as possible and take preventive action thereof. Such a system design and implementation needs an analysis phase during which the system to design and its environment are analyzed and decomposed. This approach simplifies the understanding of the intersection crossing problem by applying transformations that reduce its complexity. It begins with a thorough analysis of accidents at intersections and providing the main characteristics of these accidents. From the type and severity of accident scenarios, a classification of relevant scenarios is made. The proposed methodology establishes a strong and intuitive link between use cases on one hand and requirements and functional architecture on the other. Moreover, coherency is increased as the hierarchy of use cases affects the hierarchy in functional architecture. [ABSTRACT FROM AUTHOR]

Photonic cat states stored in high-Q resonators show great promise for hardware efficient universal quantum computing. We propose an approach to efficiently prepare such cat states in a Kerr-nonlinear resonator by the use of a two-photon drive. Significantly, we show that this preparation is robust against single-photon loss. An outcome of this observation is that a two-photon drive can eliminate undesirable phase evolution induced by a Kerr nonlinearity. By exploiting the concept of transitionless quantum driving, we moreover demonstrate how non-adiabatic initialization of cat states is possible. Finally, we present a universal set of quantum logical gates that can be performed on the engineered eigenspace of such a two-photon driven resonator and discuss a possible realization using superconducting circuits. The robustness of the engineered subspace to higher-order circuit nonlinearities makes this implementation favorable for scalable quantum computation. Quantum Computing: An engineered quantum box for Schrodinger's cat Efficient preparation of the so called photonic Schrodinger's cat states, is possible by engineering the energy levels in a quantum box. We propose an approach for fast, high-fidelity preparation and manipulation of cat states in a nonlinear cavity by the use of a parametric drive. This preparation is robust against single-photon loss from the cavity and as we show, can be easily realized using superconducting circuits. The robustness of the engineered subspace to higher-order circuit nonlinearities makes this implementation favorable and of immediate practical importance for realization of a scalable, hardware efficient platform for universal quantum computation. Our scheme offers significant improvements over existing techniques for preparation of cat states which become increasingly burdensome because of noise and for large sized cats. [ABSTRACT FROM AUTHOR]